Apparatus for manufacturing closed-cell foam and methods thereof

Abstract

The present invention provides an apparatus and a method for manufacturing a closed-cell foam. The apparatus comprises one, two or more processing units and a terminal unit. Each of the processing units includes a recess for accommodating one single slab to be expanded to the closed-cell foam. The apparatus also includes a sealable trans-unit gas system for delivering foaming gas, and a sealable trans-unit liquid system for controlling the temperature of the units. The invention exhibits numerous technical merits such as better cost-effectiveness, higher production efficiency, easy and convenient one-step foam preparation, higher precision in controlling the foam's Barcol hardness, and environmentally friendly process, among others.

1 . An apparatus  01  for manufacturing a closed-cell foam comprising one, two or more processing units (U1, U2 . . . Un) and a terminal unit Ut, wherein each of the processing unit(s) includes:
 a main body  02  with a front side  02 F and a rear side  02 R, wherein the front side  02 F has a recess  03  for partially or fully accommodating one single slab  04  made of dense material with a density D0, wherein the slab  04  is to be expanded to the closed-cell foam  60  having a density Df<D0, and wherein the recess  03 's mouth  03 M can be pressed against the rear side  02 R of another processing unit or a side  02 T of the terminal unit Ut to seal the mouth  03 M; 
 a gas entry conduit  08  configured for delivering a gas flow to the recess  03  through the main body  02 ; 
 a gas exit conduit  09  configured for releasing the gas within the recess  03  through the main body  02 ; and 
 a heating and cooling system  20  for controlling the temperature of all the processing unit(s) and the terminal unit. 
 
     
     
         2 . The apparatus according to  claim 1 , wherein each of the processing unit(s) further comprises a gas pumping channel  06  and a gas releasing channel  07 ; wherein the gas entry conduit  08  is configured for diverting a gas flow from the gas pumping channel  06  to the recess  03  through the main body  02 ; and wherein the gas exit conduit  09  is configured for the gas within the recess  03  to exit into the gas releasing channel  07  through the main body  02 . 
     
     
         3 . The apparatus according to  claim 1 , wherein the processing units and the terminal unit are stacked or arranged in serial vertically or horizontally, preferably vertically with the terminal unit located at the highest position. 
     
     
         4 . The apparatus according to  claim 1 , wherein the slab  04  is made of a dense material selected from polyvinylidene difluoride (PVDF), Perfluoroalkoxy alkanes (PFA), Polypropylene (PP), Polyethylene (PE), Polyamide (PA), Polyvinyl chloride (PVC), Ethylene-vinyl acetate (EVA), Thermoplastic polyurethane (TPU), Polyether ether ketone (PEEK), block copolymers of polyether and polyamide such as Pebax®, or any combination thereof. 
     
     
         5 . The apparatus according to  claim 1 , wherein the terminal unit Ut, unlike each of the processing units, does not have gas entry conduit  08  and gas exit conduit  09 . 
     
     
         6 . The apparatus according to  claim 1 , wherein the rear side  02 F of each processing unit is flat, and wherein said side  02 T of the terminal unit Ut is also flat; or
 wherein the rear side  02 F of each processing unit has a recess  05  with a mouth  5 M that conforms to mouth  3 M, wherein the side  02 T of the terminal unit Ut has a recess  05  with a mouth  5 M that also conforms to mouth  3 M; and wherein mouth  03 M of one processing unit and mouth  5 M of another processing unit or the terminal unit can be pressed against each other to seal both mouths ( 03 M,  05 M), forming a larger enclosed gas-tight space ( 03 & 05 ) for accommodating the single slab  04 .   
     
     
         7 . The apparatus according to  claim 1 , further comprising 2, 3, 4 or more sliding rods  13  to align all the processing units and the terminal unit in serial, and wherein each main body  02  has 2, 3, 4 or more through holes  14  for the sliding rods  13  to pass through. 
     
     
         8 . The apparatus according to  claim 2 , further comprising a mechanical presser  30 , and wherein the processing units (U1, U2 . . . Un) and the terminal unit Ut can be pressed against each other using the mechanical presser  30  so that (1) gas pumping channel  06  in one processing unit is connected to that of neighboring unit(s), and (2) gas releasing channel  07  in one processing unit is connected to that of neighboring unit(s), forming a sealed trans-unit gas system  69  for the gas flow. 
     
     
         9 . The apparatus according to  claim 8 , further comprising a gas source  70  for delivering a gas medium around each of the slabs  04  through the sealed trans-unit gas system  69  and dissolving or diffusing the gas molecules in each of the slabs  04 . 
     
     
         10 . The apparatus according to  claim 1 , wherein the heating and cooling system  20  comprises a liquid pumping channel  10 ; a liquid releasing channel  11 ; and a liquid circulating pipeline network  12  within the main body  02  configured for transferring at least a portion of the liquid flow from the liquid pumping channel  10  to the liquid releasing channel  11 , and controlling the temperature of the main body  02  by thermal exchange between the liquid flow and the main body  02 . 
     
     
         11 . The apparatus according to  claim 10 , wherein the processing units (U1, U2 . . . Un) and the terminal unit Ut can be pressed against each other using a mechanical presser  30  so that (1) liquid pumping channel  10  in one processing unit is connected to that of neighboring unit(s), and (4) liquid releasing channel  11  in one processing unit is connected to that of neighboring unit(s); forming a sealed trans-unit liquid system  79  for the liquid flow. 
     
     
         12 . The apparatus according to  claim 11 , further comprising a liquid pump  80  for circulating a heated liquid flow through the sealed trans-unit liquid system  79 . 
     
     
         13 . A method of manufacturing a closed-cell foam using the apparatus according to  claim 1 , comprising:
 (i) placing one single slab  04  made of dense material having a density D0 in the recess  03 ;   (ii) engaging the processing units (U1, U2 . . . Un) and the terminal unit Ut with each other by pressing or clamping them against each other, so that the recess  03 's mouth  03 M is pressed against the rear side  02 R of another processing unit or a side  02 T of the terminal unit Ut to seal the mouth  03 M;   (iii) delivering a gas medium with a predetermined pressure P that is higher than the atmospheric pressure P0 around each of the slabs  04 ;   (iv) adjusting the temperature of the gas medium as well as the slabs  04  to a predetermined temperature T using the heating and cooling system  20 ;   (v) dissolving or diffusing an amount of the gas molecules into each of the slabs  04  under the predetermined pressure P and the predetermined temperature T for a predetermined time period t;   (vi) lowering the pressure of the gas medium around each of the slabs  04  down to the atmospheric pressure P0 and disengaging the processing units (U1, U2 . . . Un) and the terminal unit Ut from each other, to allow each of the slabs  04  be expanded to the closed-cell foam  60  having a density Df<D0.   
     
     
         14 . The method  according to 13 , wherein each of the processing unit(s) further comprises a gas pumping channel  06  and a gas releasing channel  07 ;
 wherein, in step (ii), the gas pumping channel  06  in one processing unit is connected to that of neighboring unit(s) and the gas releasing channel  07  in one processing unit is connected to that of neighboring unit(s), forming a sealed trans-unit gas system  69  for the gas flow; and 
 wherein, in step (iii), a gas medium with a predetermined pressure P that is higher than the atmospheric pressure P0 is delivered to around each of the slabs  04  through the sealed trans-unit gas system  69 . 
 
     
     
         15 . The method  according to 13 , further comprising step (vii) of applying the closed-cell foam  60  having a density Df in a final product for end-users or consumers without further changing of the density Df or hardness of the foam  60 ; wherein the slab  04  is obtained from industrial suppliers, and it remains “as is” when it is subject to step (i). 
     
     
         16 . The method  according to 13 , wherein the slab  04  is made of a dense material selected from polyvinylidene difluoride (PVDF), Perfluoroalkoxy alkanes (PFA), Polypropylene (PP), Polyethylene (PE), Polyamide (PA), Polyvinyl chloride (PVC), Ethylene-vinyl acetate (EVA), Thermoplastic polyurethane (TPU), Polyether ether ketone (PEEK), block copolymers of polyether and polyamide such as Pebax®, or any combination thereof, and
 wherein the gas medium is carbon dioxide or a mixture of carbon dioxide and nitrogen with a molar ratio of carbon dioxide to nitrogen in a range of from 3:1 to 9:1. 
 
     
     
         17 . The method  according to 13 , wherein the predetermined pressure P is in the range of from 2 to 100 MPa, preferably in the range of from 5 to 60 MPa, and more preferably in the range of from 10 to 30 MPa;
 wherein the predetermined temperature T is in the range of from 50° C. to 300° C., preferably in the range of from 100° C. to 200° C., and more preferably in the range of from 130° C. to 180° C.; and   wherein the predetermined time period t is in the range of from 1 hours to 48 hours, preferably in the range of from 2 hours to 30 hours, and more preferably in the range of from 3 hours to 18 hours.   
     
     
         18 . The method according to  13  for producing a closed-cell foam  60  with Barcol hardness Y, wherein the time period t (in the unit of hour) for dissolving or diffusing an amount of the gas molecules into each of the slabs  04  is determined by an equation t=(100−Y)/C, wherein C is a constant depending on the predetermined pressure P and the predetermined temperature T. 
     
     
         19 . The method  according to 13 , for producing a closed-cell PVDF foam  60  with Barcol hardness Y, wherein the time period t (in the unit of hour) for dissolving or diffusing an amount of the gas molecules into each of the slabs  04  is determined by an equation t=(100−Y)/5,
 wherein the gas is CO2, the predetermined pressure P=15 MPa, and the predetermined temperature T=155° C.; and 
 preferably wherein t ranges from 4 to 12 hours and Y, accordingly, ranges from 80 B to 40 B. 
 
     
     
         20 . The method  according to 13 , further comprising aligning the processing units (U1, U2 . . . Un) and the terminal unit Ut with one or more sliding rods  13  before step (ii); wherein said adjusting the temperature of the gas medium as well as the slabs  04  to a predetermined temperature in step (iii) is carried out using a sealed trans-unit liquid system  79  to circulate a heated liquid flow such as oil within bodies of the processing units (U1, U2 . . . Un) and the terminal unit Ut.